How Do Electric Trailer Brakes Work?

How Do Electric Trailer Brakes Work?Hitch-up the travel trailer, and you are ready to go! If you can't wait when adventure awaits, you rarely think about stopping. But when you do need to slow down or stop along the way, the trailer's braking system is essential to towing safely. Electric braking systems are most commonly installed on travel trailers. We wanted to know how the electric trailer brakes work with my rig so, we researched this type of braking system to find the answer.

Electric trailer brakes are built into the wheel assembly of a trailer. The brakes must be electrically connected to the tow vehicle, via a wiring harness, in order to work. Electric trailer brakes use electromagnetic brake drums to slow or stop the spinning motion of the trailer’s wheels. A brake controller, mounted inside the cab of the tow vehicle, is used to activate the electric braking system. A brake controller regulates the amount of power transferred from the tow vehicle to the trailer’s electric brakes.

Knowing how electric trailer brakes work is one of many steps to make sure your trailer is road-ready before you get underway. Keep reading to learn how to test and adjust the electric trailer brakes. We will also discuss other types of auxiliary braking systems that you might find on trailers and campers.

Do Electric Trailer Brakes Work in Reverse?

Yes! Electric trailer brakes do work in reverse. When you engage the tow vehicle’s brake pedal, the brake controller will activate the electric trailer brakes regardless of whether you are driving forward or reversing.

How Do You Test Electric Trailer Brakes?

Testing your electric trailer brakes is a fairly simple process. Ideally, you will want to be located in an open, level area with plenty of room for starting and stopping.

To get started, make sure the trailer’s wiring harness is securely plugged into the tow vehicle. Allow a moment for the brake controller to calibrate. Most brake controllers do this automatically when you plug-in the wiring harness. A signal light on the brake controller will alert you when calibration is complete.

Prior to driving, you can adjust any personal settings on the brake controller, such as the screen brightness or angle of the interface. The brake controller should be within easy reach and clear view.

Now you are ready to test the electric trailer brakes. Drive forward at approximately 25-mph then, press the brake pedal to engage the brakes how the vehicle stops will determine whether you need to adjust the brake controller to transfer more or less power to the electric trailer brakes.

  • If your vehicle stops too slowly, this indicates the brake controller is not transferring enough power to the electric trailer brakes. You should increase the brake controller’s output and test the brakes again.
  • If your vehicle stops too abruptly, this indicates the brake controller is transferring too much power to the electric trailer brakes. You should decrease the brake controller’s output and test the brakes again.

Continue to test the brakes until the vehicle stops smoothly. Set properly, the brake controller enables the tow vehicle and trailer to slow or stop at the same rate of deceleration.

When Should I Use Manual Activation?

Manual activation enables the driver to manually stop the trailer without engaging the brake pedal, simply by pressing a button on the brake controller. Manually activating the electric trailer brakes is useful to correct trailer sway. You can also use manual activation to gradually slow the trailer while traveling down a long, steep incline.

How Do You Adjust Electric Trailer Brakes?

Follow the manufacturer’s instructions to adjust your brake controller. Although similarly adjusted, different controllers will have different settings. Use the power knob, as indicated by the manufacturer’s instructions and follow these steps:

  1. Couple the trailer to the tow vehicle and plug-in the electrical connection.
  2. Drive the tow vehicle and trailer to an open, relatively flat location. Proceed at slow to moderate speed, and use the brake controller’s manual activation to engage the electric trailer brakes along the way. Some manufacturers will recommend “warming-up” the brakes prior to adjustment; if so, follow the instructions provided for your brake controller.
  3. Stopped, keep the tow vehicle’s engine running, and set the brake controller to the mid-point setting.
  4. Drive up to a maximum of 25-mph and release the accelerator. Adjust the brake controller to its maximum output setting.
  5. Press the brake pedal and assess how the vehicle stops. If the wheels lock-up or the vehicle comes to an abrupt stop, lower the brake controller’s output setting.
  6. Repeat the drive and brake test. Continue to adjust the brake controller’s output settings until the electric trailer brakes sufficiently stop the trailer.

If you plan to tow the same trailer repeatedly, you will rarely need to re-adjust the brake controller. However, if the weight of your trailer changes or you tow a different trailer, adjust the brake controller accordingly.

Adjusting the brake controller for weather conditions or rough surface conditions can also be helpful. Towing on slippery or gravel surface conditions, you might want to reduce the brake controller’s output to prevent the trailer from skidding.

Are There Different Types of Brake Controllers?

The brake controller is a key component to the electric trailer braking system because, without a controller, the system would not work. Using a brake controller enables you to fine-tune the trailer's braking. There are two types of brake controllers:

Time Delay (Solid State) Brake Controllers

A time delay brake controller responds to the pressing of the brake pedal by transferring a pre-set amount of power to the electric trailer brakes. A slight delay occurs after pressing the brake pedal, as the controller ramps up over a fixed rate of time to provide maximum power output. The amount of braking power and rate of application are both pre-set by the driver and can be adjusted depending on trailer weight and surface conditions.

Key Advantages:  Time delay brake connectors are less expensive than proportional brake controllers and can be mounted at any angle in the cab of the tow vehicle.

Proportional (Inertia-Based) Brake Controllers

A sensor is activated in the proportional brake controller when the brake pedal is pressed. The sensor determines the rate at which the vehicle is slowing or stopping, and relays this information to the brake controller to send out enough power for the electric trailer brakes to slow or stop with the same intensity. Properly adjusted, the proportional brake controller enables the tow vehicle and trailer to decelerate at the same speed.

Key Advantages:  Increased braking efficiency will reduce the overall wear of brakes on both the tow vehicle and the trailer. Proportional brake controllers are able to adapt to changing braking conditions resulting in smooth, general braking or heavy-duty, emergency braking.

How Much do Brake Controllers Cost?

When selecting a brake controller, you not only want to consider time delay versus proportion but also individual controller features such as the type of display, warning alert options for brake malfunction, and mounting positions. If you are towing a travel trailer with more than one or two axles, make sure the brake controller is compatible.

Time delay brake controllers are affordable. Prices range from as low as $37 for the basic, Draw-Tite 5100 brake controller to $50 for the Reese 74642 Brakeman Timed Compact brake controller.

Proportion brake controllers are slightly more expensive, ranging from $60 to upwards of $200. Compare these mid-range options at $70 for the Tekonsha 90160 Primus IQ  brake controller and $96 for the CURT 51140 TriFlex brake controller.

How Do You Test an Electric Brake Controller Without a Trailer?

You can test an electric brake controller without a trailer by using a circuit tester. Have a partner available to help, as you will need to access the rear of the tow vehicle and the interior brake pedal simultaneously.

Connect one pin of the circuit tester to the output pin and ground the other. The circuit tester will put a slight amperage draw on the brake controller’s output circuit, simulating a trailer connection. Press the brake pedal while the circuit tester is connected. Watch the brake controller; it should function normally while the brake pedal is engaged.

If the brake controller does not function normally during this test, you might need to conduct a more in-depth test or consult a reputable mechanic to diagnose the issue.

Do I Need a Brake Controller for Electric Brakes?

You absolutely need a brake controller to operate electric trailer brakes. Without a brake controller, the electric trailer brakes will not work.

What is a Breakaway System?

A breakaway system is an emergency braking system that automatically engages the electric brakes if the trailer detaches from the tow vehicle. Electric trailer brakes and surge trailer brakes are equipped with breakaway systems.

What Are Other Types of Braking Systems Available for Travel Trailers?

Although electric brakes are most commonly found on travel trailers, other types of auxiliary braking systems do exist. Selecting the best braking system for your rig depends on how you intend to use the trailer and the weight of the trailer.

Surge Brakes

Surge brakes do not require an electrical connection in order to work. Instead, they are powered by inertia and operate hydraulically. The surge braking system is self-contained on the trailer and requires very low maintenance. Surge brakes must be deactivated prior to reversing to prevent the trailer from stopping when you want to back-up.

Boat trailers are commonly equipped with surge brakes because the trailer tongue is routinely submerged in water as boats are launched and hauled. Hydraulic braking systems are more resistant to wear and corrosion from water than electrical braking systems. Surge brakes are also very common on rental trailers, as drivers might be unfamiliar with electrical braking system controls.

Air Pressure Brakes

Air pressure braking systems rely on stored air pressure produced by an engine-mounted compressor in the tow vehicle. On trailers, air pressure brakes have a spring-loaded actuator located at each wheel. Air pressure is released to activate the brakes, generating force to slow or stop the spinning motion of the wheels.

If there is a malfunction in the air pressure braking system, the brakes will lock-up and stop the trailer. Air pressure systems do not require a breakaway system.

Are Trailer Brakes Required by Law?

Most state laws require auxiliary braking systems on trailers weighing 3,000-lbs or more. Check AAA’s listing of trailer brake laws by state to find out if your trailer is ready for the road.

There are many considerations for trailer braking systems, but now you know how electric trailer brakes work. The next time you hitch-up the travel trailer, make sure you start your trip with a brief STOP to test your trailer's braking system. You will be reassured to know your trailer is being towed safely using electric trailer brakes.

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